180 THE MICROSCOPE. 



rhizophyllus) whose frond, bending over to the ground, has given 

 root to a new plant. The new plant may produce a long frond 

 which in its turn will root a third plant. Mr. Stearns has seen 

 three steps taken in one season, though generally one is suffici- 

 ent. 



Besides propagating in this manner, this fern propagates in 

 the usual way, by means of spores. A section of leaf bearing 

 spores is shown in figure 2, a closed spore case (sporangium) in 

 figure 4. and a sporangium opened in order to discharge its 

 spores in figure 3, these being magnified 400 diameters. 



This peculiar "walking" method of producing new plants re- 

 minds us of the Ban van tree of India. 



LIGHTING A MICROSCOPE WITH THE 

 INCANDESCENT LAMP. 

 By JOSEPH HOGBOTHAM, 



LONDON, ENGLAND. 



At a recent microscopical exhibition, it was amusing to no- 

 tice among the great variety of illuminating apparatus includ- 

 ing oil lamps of all kinds, gas burners, etc, one instrument ap- 

 parently without any light. On closer examination, however, 

 it was found that a small incandescent lamp was concealed near 

 the stage in such a manner as to give no light except upon the 

 object. The object was beautifully illuminated. The arrange- 

 ment is described in The Optician as follow : 



The lamp was situated in the focus of a small silvered para- 

 bolic reflector whose wide end was covered by a blackened 

 brass plate having a short brass tube screwed into it. This part 

 of the apparatus looked like a swab used by gunners for clean- 

 ing out the bore of a cannon after a shot has been fired. In- 

 serted into the small tube was a solid rod of clear glass having 

 both ends ground perfectly j^lane, polished and at right angles 

 to the axis of the glass rod. This rod may be inserted loosely 

 or it may be soldered to the tube. It was blackened on the 

 outside with Brunswick black or some dark japan, so that there 

 was absolutely no light visible along the rod other than that 

 which was projected from the end farther away from the light. 

 The whole apparatus was so adjusted that this beam of light 



